The present invention relates to a method of generating cold and using it either directly or indirectly after transient storage and restitution, wherein cooling and/or partial freezing of a cold-accumulating and cooling liquid partially filling a cooling cell is effected by injecting a refrigerant at least partly in the liquid state into a mass of said cold-accumulating and cooling liquid, contained in said cooling cell, and vaporizing this refrigerant directly in this liquid, and by collecting the refrigerant in the gaseous state at the upper part of this cell, above a free surface of the cold-accumulating and cooling liquid, and wherein the cold-accumulating and cooling liquid is withdrawn from this cell, and is conveyed in a cold-utilization circuit and/or to at least one cold-storage cell, then is reintroduced into said cooling cell.
It also relates to a device for implementing this method, including at least one cooling cell containing a cold-accumulating and cooling liquid, partially filling this cell, means for injecting and vaporizing a refrigerant at least partly in the liquid state into a mass of cold-accumulating and cooling liquid, means for collecting the refrigerant in the gaseous state at the upper part of this cell, above a free surface of the cold-accumulating and cooling liquid, and means for withdrawing cold-accumulating and cooling liquid from this cell and for conveying it in a circuit for cold-utilization and/or to at least one cold-storage cell, and then reintroducing it into the cooling cell.
In recent years, various methods of generating and accumulating cold have been developed which seek to solve the problem arising from the fact that the diagram of utilization of cold in an installation is generally irregular and often passes through a transient maximum.
In a particularly advantageous method of generating and accumulating cold described in Swiss Pat. No. 628,417 filed on 6.01.1978, crystals of a frozen cold-accumulating and cooling liquid are produced - this liquid generally consisting of water or an aqueous solution - in a mass of this liquid contained in a crystallizing cell and vaporizing a refrigerant injected into this liquid mass, while collecting and aspirating this refrigerant in the gaseous state at the top of this crystallizing cell above the free surface of this liquid mass. The mixture of cold-accumulating and cooling liquid and crystals of this frozen liquid thus formed is brought into a cold-storage cell where these crystals are accumulated in the form of a solid mass impregnated with liquid.
A first problem encountered with this method is that the microscopic crystals produced in the crystallizing cell, the specific mass of which is less than that of the cold-accumulating and cooling liquid, tend to be agglomerated and accumulated by decantation in the vicinity of the free surface of the accumulating liquid. This leads to the risk of a plug of agglomerated crystals being formed in the vicinity of the free surface of the accumulating liquid contained in the crystallizing cell. This plug rapidly fills the space surmounting the injector, which interferes with the vaporization of the refrigerant and/or necessitates its interruption.
A second problem encountered with this method arises from the difficulty of transporting said crystals and/or accumulating them in the form of a porous, homogeneous and compact mass, because these crystals form with the accumulating liquid withdrawn from the cell a heterogeneous mixture, of partly solid consistency, of crystal agglomerates of large dimensions which may go up to several centimeters, these agglomerates being produced in the bulk of cold-accumulating and cooling liquid and/or detached from the above-mentioned plug.
A third problem encountered with this method is that a part of the gaseous refrigerant injected and/or produced by vaporization in the crystallizing cell risks being carried along with the cold-accumulating and cooling liquid, containing said crystals, withdrawn from the cell to be conveyed in a circuit for exchanging cold, directly or after its passage in a cold-storage cell. This results in multiple drawbacks, one of which is the neccessity of frequently purging the different elements of the circuit traversed by the conveyed mixture.
A fourth problem encountered with this method is that the known systems for implementing it are confronted with problems of icing of the injector for the refrigerant. This icing is observed on the exterior of the injector which is immersed in the mass of cold-accumulating and cooling liquid, but also partly within the body of the injector when the refrigerant contains even a minute proportion of this cold-accumulating and cooling liquid. Various mechanical or thermal means are presently used for periodically deicing the injector. However, these current means lower the thermodynamic efficiency of the installation and are costly and of low reliability. In addition, they necessitate periodic interruption of the cold-production cycle, which decreases the mean refrigerating capacity of the installation.